1. Field of the Invention
The present invention is generally related to a replaceable portion of a marine drive unit and, more particularly, to a replaceable leading edge portion which is configured to absorb energy during impact in order to prevent damage to a permanent rearward portion of the drive housing structure.
2. Description of the Prior Art
Those skilled in the art of marine drives are aware of many ways in which the drive can be damaged. For example, a gear case of a marine drive can impact a submerged or partially submerged object as a marine vessel passes over that object. Typically, the leading surface of the gear case, skeg, and drive shaft housing can strike the submerged or partially submerged object and cause severe damage to those portions of the marine propulsion unit. Various devices have been suggested for use in providing a replaceable element associated with the marine drive.
U.S. Pat. No. 3,939,795, which issued to Rocka on Feb. 24, 1976, describes an outboard motor protective cover. The cover for the lower portion of an outboard motor includes the skeg, rudder and propeller shaft housing to increase the strength of the motor parts covered and protect such parts against water damage and wear. A reinforcing rib may be added for additional strength and an insert plate may be inserted in the cover to replace a missing skeg.
U.S. Pat. No. 4,832,635, which issued to McCormick on May 23, 1989, discloses a nose construction for the gear case of a marine drive. The drive unit includes a lower propeller torpedo housing of generally cylindrical configuration having a longitudinal centerline. A propeller shaft is mounted in the housing for rotation on an axis offset from the centerline. The shaft is journalled in a forward bearing assembly which is held in place by a support adjustably mounted to the housing and on the offset axis. A nose is removably secured to the forward housing end by a mounting bolt which extends into the support on the offset axis. A single multi-purpose opening or port in the forward end of the nose communicates to an interior entry passage in the nose. The entry passage, in turn, merges into a pair of passage branches. One branch is disposed on the offset propeller shaft axis and receives the mounting bolt. The other branch is positioned to communicate with the cooling water passages in the lower unit and which lead to the marine drive engine. A torque retention and sealing member is disposed between the support and the nose. Furthermore, a torque retention and sealing member is disposed between the bolt head and the inner end of its passage branch.
U.S. Pat. No. 5,000,709, which issued to Bergeron on Mar. 19, 1991, describes a universal nose cone and method for profiling same. The nose cone has a cavity with height, width and depth dimensions to accommodate a plurality of different water craft drive lower housings so that once the nose cone has been suitably profiled a desired one of these lower housings can be adhesively secured to the gear casing for which it was profiled with the edge of the cavity engaging that housing thereby to streamline that lower housing to improve performance of the water craft using that drive housing.
U.S. Pat. No. 5,007,868, which issued to Fry on Apr. 16, 1991, describes a replaceable skeg for a marine propulsion device. The skeg device is provided and includes a tapered dovetail tongue and groove joint between top of the skeg and lower portion of a gear case housing on the marine propulsion device. When the skeg is hit by an underwater obstruction it will fracture at the joint and break away, leaving the lower portion of the gear case housing intact and undamaged in which another skeg can be installed thereto.
U.S. Pat. No. 5,007,869, which issued to Zoellner on Apr. 16, 1991, describes a propeller saving device. The propeller guard device includes a laterally extending fin and a vertical extension or sleeve. The fin and sleeve can be manufactured as a single item. The vertical sleeve is attached to the midline area of the fin with the leading edge of the sleeve being generally co-terminus with the leading edge of the fin. The fin is at least as wide as the rotational path of the propeller blades. The singular fin extends laterally on either side of the sleeve in a generally coplanar relationship. The leading edge of the fin is elevated from three to five degrees higher than the trailing edge of the fin. The trailing edge of the fin is located forwardly of the rotational path of the propeller blades or is lengthened and extends toward the rear of the device to the extent of being even with the midline of the rotational path of the propeller blades.
U.S. Pat. No. 5,178,565, which issued to Jacobson on Jan. 12, 1993, describes a lower unit guard. The guard attachable to the lower unit of an outboard motor is intended to prevent direct impact between submerged hazards and the elements of the lower unit. The guard includes two angle brackets, a rigid bar attached to the angle bracket at a top end, and a skeg pocket and fin attached to a lower portion of the bar. The guard descends from a position forward of and substantially level with the cavitation plate to a point below the. skeg. The guard prevents damage to the entire lower unit, including the propeller, upon impact with a submerged obstacle.
U.S. Pat. No. 5,224,889, which issued to Hickey on Jul. 6, 1993, describes a propeller guard. The device is intended to protect the propeller of a boat from damage caused by striking underwater obstacles. This can occur when the boat is moving in any direction relative to the obstacles. The invention is intended to improve the movement of the boat along the water.
U.S. Pat. No. 5,277,632, which issued to Davis on Jan. 11, 1994, describes a boat motor replacement skeg. An outboard motor replacement skeg is thin and flat and has a cavity formed in one of its edges. The replacement skeg is slid over the stub which remains after the original skeg is broken off and is fastened to the skeg stub with silicone sealant and rivets. As an alternative, the replacement skeg may be part of an original design to replace a specific breakaway skeg having a particular mounting structure.
U.S. Pat. No. 5,399,113, which issued to DeMasi on Mar. 21, 1995, describes a protector against submerged objects. The lower portion of the outdrive of a sterndrive motor or of an outboard motor for boats is further protected from damage on striking submerged objects. Protection at low speed is gained by providing sharp or knife-like edge formed of rubber on the leading of the lower portion to gain the resiliency to cushion from damage at low speeds. Lower portions are typically pivotally mounted with respect to the rest of the motor to enable trim adjustment by a cylinder and piston arrangement.
U.S. Pat. No. 5,501,622, which issued to Phelan on Mar. 26, 1996, describes a marine mammal guard. The guard is intended for use with an outboard motor having a drive shaft housing, an anti-cavitation plate, a lower support unit, a gear casing, a skeg and a propeller hub with a plurality of propeller blades radially extending therefrom. The guard comprises a protective housing having a pair of forward intake ports and a rearward exit port. A mechanism is provided for securing the protective housing to the lower support unit.
U.S. Pat. No. 5,536,188 which issued to Porta on Jul. 16, 1996, describes a nose cone method and apparatus. The nose cone attachment for an outboard motor propeller gear case has a molded polymer housing shaped to fit over the front and sides of the outboard propeller gear case and has an aerodynamic nosepiece shape in the front thereof with a plurality of water inlets thereon. The molded polymer housing has open water channels or plenums therein which form wide passageways with the gear case housing sides when the nose cone attachment is attached over the gear case housing. The open water channels are positioned to fit over the gear case water inlets.
U.S. Pat. No. 5,643,023, which issued to Sober on Jul. 1, 1997, describes a marine engine gear case cover. The skeg cover may be fitted onto either a damaged skeg or a new skeg to prevent shaft, gear, or propeller damage. The invention is constructed such that it is inexpensive and may be quickly and easily installed by a boat owner.
U.S. Pat. No. 5,772,481, which issued to Alexander et al. on Jun. 30, 1998, discloses a skeg construction for a marine propulsion unit. The skeg assembly includes a generally U-shaped saddle that is removably attached to the lower torpedo section of the gear case of the propulsion unit and a thin wedged shaped skeg extends downwardly from the saddle. During planing conditions of the boat, the water line is slightly below the lower torpedo section so that the saddle is out of the water. The side surfaces of the skeg have opposed water intake openings each of which is bordered rearwardly by a laterally projecting shoulder that terminates in a vertical edge and the intake openings are bordered forwardly by a curved surface that connects the side surfaces of the skeg. The water intake openings communicate with a water passage in the skeg which, in turn, communicates with a water passage in the torpedo section so that water can be delivered to the cooling system of the propulsion unit.
U.S. Pat. No. 6,168,483, which issued to McIntosh on Jan. 2, 2001, describes a deflecting propeller guard. The guard comprises a pair of adjacent deflector plates slanting downwardly and rearwardly from a front apex location to provide downwardly and laterally facing deflection surfaces. There is a rear guard section having two guard plates positioned adjacent to one another and extending outwardly and upwardly at a moderate slant from a central axis.
U.S. Pat. No. 6,503,110, which issued to Lammli on Jan. 7, 2003, describes a lower unit guard for an outboard motor. The guard includes a mounting adapted to be secured onto a flange on a housing of a boat motor. The mounting has a leading edge. A skeg receiving pocket is provided which is adapted to receive a skeg of the outboard motor. The skeg receiving pocket is adapted to accommodate in close fitting relation the skeg in its entirety. The skeg receiving pocket has a leading edge, a trailing edge and a bottom edge. A reinforcement member is adapted to fit the contours of a lower unit of the boat motor. The reinforcement member has an upper extremity secured to the leading edge of the mounting and a lower extremity secured to the leading edge of the skeg receiving pocket.
Those skilled in the art of automobile design are familiar with various structures and configurations which are designed for the purpose of absorbing energy and sacrificing the energy absorbing object in order to protect other components.
U.S. Pat. No. 6,406,081, which issued to Mahfet et al. on Jun. 18, 2002, describes an energy absorber system. The system for a vehicle includes an elongated energy absorber including a flanged frame for attachment to a reinforcing beam and a body including a plurality of spaced apart tunable crush boxes capable of deformation and progressive collapse upon impact for absorbing the energy of impact.
U.S. Pat. No. 6,669,251, which issued to Trappe on Dec. 30, 2003, describes a bumper beam and bumper assembly including a bumper beam. The bumper assembly for an automotive vehicle includes a beam and an energy absorber. The energy absorber includes a flanged frame for attachment to the beam and a body extending from the frame. The body includes a first transverse wall, a second transverse wall spaced from the first wall and a plurality of tunable crush boxes extending therebetween. The bumper assembly has greater than fifty percent efficiency.
U.S. Pat. No. 6,679,544, which issued to Hubbert et al. on Jan. 20, 2004, describes a molded energy absorber. The absorber includes two sections connected by a plurality of hinge elements. One section has a plurality of telescopically crushable tubular cylinders integrally molded thereon. The two sections are folded together and the energy absorber attaches to a structural vehicle pillar on the inside of the vehicle. Upon impact, the tubular cylinders are fractured and crush telescopically, thereby dissipating much of the impact energy.
U.S. patent application Ser. No. (M09719), which was filed by Misorski et al. on Feb. 17, 2004, discloses a marine drive unit overmolded with a polymer material. A marine propulsion system drive unit is provided with a polymer layer to protect its outer surface from abrasion and corrosion. The polymer layer is injection molded around the outer surface of a metallic gear case structure or drive shaft housing to provide a coat which is approximately three millimeters thick and which will resist scratching and corrosion. The polymer layer can be a glass filled polymer or a carbon filled polymer. An adhesion promoter can be used to enhance the bonding and intimate contact between the inner surface of the polymer layer and the outer surface of the metallic gear case structure or drive shaft housing.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Various types of components and devices are familiar to those skilled in the art for the purpose of attaching those components to marine propulsion devices for the purpose of protecting or replacing portions of the marine drive housing. These components, as described above, can be used to protect or replace the skeg and other leading portions of the marine drive housing. In addition, those skilled in the art of energy absorption are familiar with various types of structures and configurations that are particularly designed to absorb energy during an impact with another object so that other components can be protected from damage during that impact.
It would be significantly beneficial if a marine drive unit could be protected by providing a leading edge structure that absorbs energy in the event of an impact with a submerged or partially submerged object, such as a log, in a way that protects the majority of the submerged portion of the drive housing from damage. It would also be significantly beneficial if this type of protection device could be easily installed and accurately positioned. when replacement of a damaged device is necessary. It would also be significantly beneficial if the replacement device could be configured in such a way so as to facilitate the introduction of water into the drive unit so that the water can be conducted upwardly into the cooling passages of an engine that is associated with the drive structure.